Brief summaries of tropical Atlantic activity tailored to the general public, coastal residents, and weather enthusiasts. I have been sending out these updates since 1996, and appreciate everyone's continued interest!

28 August 2013

Remembering Katrina

Today, August 28th, is a day many in the hurricane community will never forget. It was a Sunday morning, and we started the day off staring in disbelief at what had become an enormous Category 5 hurricane sitting in the central Gulf of Mexico - and heading north.

Katrina as a Category 5 hurricane on August 28th, 2005. (NOAA)

It hit Miami, FL three days prior as an intensifying Category 1 hurricane, and strengthened as it crossed over the eastern Gulf. The forecast was, and had been, accurately centered on eastern Louisiana and Mississippi for several days; the big question leading up to that landfall would be the intensity.

For many years, the "New Orleans scenario" was well-known, and had been addressed in practice drills and exercises... it's a very vulnerable city, with many areas situated below sea level. Everyone knew this would be bad; really bad. The NWS forecast office in New Orleans issued the following warning in advance of the landfall:

"MOST OF THE AREA WILL BE UNINHABITABLE FOR WEEKS...PERHAPS LONGER. AT LEAST ONE HALF OF WELL CONSTRUCTED HOMES WILL HAVE ROOF AND WALL FAILURE. ALL GABLED ROOFS WILL FAIL...LEAVING THOSE HOMES SEVERELY DAMAGED OR DESTROYED. POWER OUTAGES WILL LAST FOR WEEKS...AS MOST POWER POLES WILL BE DOWN AND TRANSFORMERS DESTROYED. WATER SHORTAGES WILL MAKE HUMAN SUFFERING INCREDIBLE BY MODERN STANDARDS."

Of course, as dire as that sounds, the end result was even worse. It made landfall on the morning of August 29th... it would become the costliest natural disaster in the history of the U.S. (~$108 billion), and was responsible for nearly 2,000 deaths. The only good news was that it weakened quite a bit prior to landfall, and came ashore as a weakening Category 3 storm (120mph winds) rather than the Category 5 (175mph winds) it was a day earlier. Watch a radar loop of the landfall... and note that the final frame also marks the time the radar there was destroyed.

It generated a devastating 27.8-foot storm surge in Mississippi, and the smaller surge in New Orleans was enough to stress the levees protecting the city beyond their breaking point. Many beachfront communities were erased from the map, particularly in Mississippi.

Observed storm surge generated by Katrina. The peak value in the ">16 feet" category was nearly 28 feet in Pass Christian, MS... the largest surge ever recorded in the U.S. (SURGEDAT)

Later that year, other major hurricanes (Cat3+) made U.S. landfall, wrapping up with Wilma on October 24th when it hit the southwestern Florida peninsula. That remains the last time the U.S. was hit by a major hurricane. I included some details on just how bizarre and unprecedented this span is in my season wrap-up last year (scroll down to the 7th paragraph).

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Author: Brian McNoldy,Senior Research Associate at University of Miami's Rosenstiel School of Marine and Atmospheric Science

"In the eye of a hurricane, you learn things other than of a scientific nature. You feel the puniness of man and his works. If a true definition of humility is ever written, it might well be written in the eye of a hurricane." -Edward Murrow, reporting on Hurricane Edna 1954